july 19, 2010thesis defense, usc experimental investigation of the effect of copper nanowires on...
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July 19, 2010 Thesis Defense, USC
Experimental Investigation of the Effect of Copper Nanowires on Heat Transfer and Pressure Drop
for a Single Phase Microchannel Heat Sink
M.S. Thesis DefenseJuly 19, 2010
M. Yakut Ali, M.S. Candidate Dr. Jamil A. Khan, Advisor
Outline of the presentation
Introduction Overview of Heat Sinks for Electronics Cooling Motivation / Problem Statement
Experimental facilities/ Setup Synthesis of Cu Nanowires on Cu Heat Sink Characterization of Cu Nanowires using SEM Flow Loop and Test Section Design & Fabrication Data acquisition and Post Processing
Results and Discussions
Summary and Future Works
July 19, 2010 Thesis Defense, USC
Image Source : http://en.wikipedia.org/wiki/Heat_sink
Overview of Heat sinks for Electronics Cooling
A heat sink is a term for a component that efficiently transfers heat generated within a solid material to a fluid medium, such as air or a liquid.
For high power electronics cooling, many alternative cooling schemes have been examined in recent years to meet this demand.
Microprocessor heat sink
Heat sinks for Electronics Cooling
Motherboard Heat sink
Liquid Cooled Microchannel Heat Sink is on The Rise
Microchannel Heat Sink
Tuckerman and Pease 1981
removal of large amount of heat from a small area
Dense package
Small foot-print cooling scheme
Larger surface area per unit volume
Dimensions from 10 to 1000 µm
Channels may be rectangular, circular or trapezoidal
Single-phase/two-phaseDixit et al. 2007
Microchannel Heat Sink
Thesis Defense, USCJuly 19, 2010
Enhancing Microchannel Heat Transfer is the Focus!
Ref. : Moore GE 1965 Electronics 38 : 114–117 and Intel Websitehttp://en.wikipedia.org/wiki/Moore's_law
Moore’s Law
Motivation
Motivation
# of Transistors in a given area doubles every 2 years due to reduction of transistor size
Advancement in Nanotechnology
Motivation
Li C. et al. 2008, Small
Chen R. et al. 2009, Nano Letters Diatz et al. 2006
July 19, 2010 Thesis Defense, USC
Mudawar et al. 2009, IJHMT
Launay et al. 2006, Microelectronics Journal
Proposed Investigation
Proposed Investigation
Thesis Defense, USCJuly 19, 2010
Cu nanowiresHeat Flux from Bottom Heat Flux from Bottom
Inlet
Outlet
Typical Microchannel Heat Sink
Nanowires Coated Microchannel Heat Sink
Synthesis of Cu nanowires on Cu heat sink Characterization of CuNWs Design and Fabrication of Experimental Thermal and Flow loop Design Experimental metrics Assessment and Comparison of the thermal performance and pressure drop results Investigation of surface Morphology before and after the heat transfer experiments
Approach:
Cu Nanowires Growth on Cu Heat Sink
Synthesis and Characterization of Nanowires on Heat Sink
Synthesis : Electrochemical technique
Tao Gao et al. 2002
Copper Heat Sink
Cu Heat Sink
PAA Template
PAA Template on Cu Substrate
Electrochemical Deposition
Washing away PAA template
July 19, 2010 Thesis Defense, USC
Growth Conditions
Voltage -0.3 V
Time 3600 s
Electrolyte CuSO4 .5H2 O+ H2SO4
Cu Nanowires Growth on Cu Heat Sink
Experimental Facilities
Flow loop
July 19, 2010 Thesis Defense, USC
Top plate/ cover plate
Base plate
Cu foil
Intermediate plate
Rubber Cushion
Cu foil
Cu heat sink
Pre-moistened filter paper
PAA template
Exploded View of the Reactor Components
Cu Nanowires Growth on Cu Heat Sink
Experimental Facilities
Digital Photographs of Reactor components
July 19, 2010 Thesis Defense, USC
Assembled Reactor
Electrochemical Work Station
Characterization of Cu Nanowires
Characterization : SEM
July 19, 2010 Thesis Defense, USC
Bare Cu Heat Sink
Cu Nanowires on Heat Sink
Experimental Facilities for Convective Heat Transfer Experiments
Flow Loop
July 19, 2010 Thesis Defense, USC
Test Section
Data AcquisitionLiquid Reservoir Gear Pump
Degasifier and Filter
Control Valve
Liquid ReservoirComputer
Schematic diagram of the flow loop
Experimental Facilities for Convective Heat Transfer Experiments
Experimental Facilities
Digital Photographs
July 19, 2010 Thesis Defense, USC
Experimental Facilities for Convective Heat Transfer Experiments
July 19, 2010 Thesis Defense, USC
Cover plate
Housing
Coolant in
Coolant out
Pressure ports
Cartridge Heater
Insulation Block
Insulation Block
Base plate / Support plate
Inlet plenum
Copper Heat Sink
Test Section
Thermocouples Location
Exploded view of Test Section Components
Experimental Facilities for Convective Heat Transfer Experiment
July 19, 2010 Thesis Defense, USC
Insulation Block
Support Plate
Cover Plate
Outlet port
Housing
O-Ring Seal
Cartridge HeaterBolts
Inlet port
Insulation Block
Assembly of the test section
Digital Photographs of Test Section Components
Summary
July 19, 2010 Thesis Defense, USC
Experimental Procedure, Postprocessing and Uncertainty Analysis
Postprocessing
July 19, 2010 Thesis Defense, USC
Sensible Heat Gain by Coolant
Power Input to Cartridge Heater
Average Heat Transfer Coefficient
Log Mean Temperature Difference
Nomenclature: ρ = Density of water at Tm
Cp = Specific Heat of Water at Tm
V = VoltageI = CurrentAht =Heat Transfer AreaTi = Inlet TemperatureTo = Outlet Temperature Ts = Surface TemperatureTm = Mean TemperatureTs,j =Heat Sink Surface Temperature Tc,j=Thermocouple readingkCu = Thermal Conductivity of Copper s = Distance from thermocouple location to top surface q’’ = Heat flux
Heat Sink Surface Temperature
Experimental Procedure, Postprocessing and Uncertainty Analysis
Postprocessing Average Nusselt Number
Hydraulic Diameter
Friction Factor
Nomenclature:
Nu= Nusselt Numberh = Average convective heat transfer coefficientDh = Hydraulic diameterkf = Thermal conductivity of the fluid at Tm Ac = Channel cross sectional areaPw = Wetted Perimeter µ = Viscosity of water at Ti
Q = Flow RateTm = Mean TemperatureL = Length of test sectionPr = Prandtl number∆p = Pressure drop
Dimensionless Hydrodynamic Axial Distance
Reynolds Number
Dimensionless Thermal Axial Distance
Experimental Procedure, Postprocessing and Uncertainty Analysis
Uncertainty Analysis
July 19, 2010 Thesis Defense, USC
Parameter Uncertainty
Dh 3%
Re 5%
q 6%
P 1%
∆TLMTD 9%
h 11%
Nu 12%
x+ 5%
x* 5%
Kline and McClintock :
Measured Parameter
Uncertainty
Pressure 0.25%
Temperature ±0.3 C ̊�
Voltage ±0.01V
Current 0.4%
Flow Rate 0.02%
Measurement Uncertainty Propagated Uncertainty
Experimental Procedure, Postprocessing and Uncertainty Analysis
Test Procedure
July 19, 2010 Thesis Defense, USC
Test
#
Reynolds
Number
(Re)
Width, w
(mm)
Height,
b (µm)
Length,
L (mm)
Hydraulic
Diameter
Dh ( µm)
Aspect ratio,
α = w/b
(Dimensionless)
1 106 5 360 26 672 13.89
2 208 5 360 26 672 13.89
3 316 5 360 26 672 13.89
4 428 5 360 26 672 13.89
5 529 5 360 26 672 13.89
6 636 5 360 26 672 13.89
Results
Results : Surface Wettability Characteristics
July 19, 2010 Thesis Defense, USC
58.070.5 E
Bare Cu Heat Sink CuNWS Coated Heat Sink
Improvement in Surface Wettability!
Results
Results : Bare Microchannel Heat Sink
July 19, 2010 Thesis Defense, USC
100 200 300 400 500 600 700 8000
1
2
3
4
5
6
7
Experimental results Hausen [39] Qu [40] Harms [41]
Re
Nu
Heat Transfer Results
Re 106 208 316 428 529 636
x+ 0.363 0.186 0.123 0.09 0.073 0.060
x* 0.067 0.032 0.021 0.015 0.012 0.010
Results
July 19, 2010 Thesis Defense, USC
Results : Bare Microchannel Heat Sink
Heat Transfer Results
0 100 200 300 400 500 600 7000
1000
2000
3000
4000
5000
6000
7000
Heat transfer coefficient
Re
h (
W/m
2k)
0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.080
1000
2000
3000
4000
5000
6000
7000
Heat transfer coefficient
x*
h (
W/m
2k)
Results
July 19, 2010 Thesis Defense, USC
Results : Bare Microchannel Heat Sink
Heat Transfer Results
0 1 2 3 4 5 6 730
35
40
45
50
55
60
Re=106Re=208Re=316Re=428Re=529Re=636
Thermocouple number along heat sink
Hea
t S
ink
Tem
per
atu
re
(EC)
Results
July 19, 2010 Thesis Defense, USC
Results : Bare Microchannel Heat Sink
Pressure Drop Results
0 100 200 300 400 500 600 7000
500
1000
1500
2000
2500
Pressure Drop
Re
Pre
ssu
re d
rop
(P
a)
0 100 200 300 400 500 600 70050
60
70
80
90
100
Calculated from experimentsMorini [43]Shah and London [44]
Re
fRe
Results
July 19, 2010 Thesis Defense, USC
Results : Comparison between Bare and CuNWs Coated Microchannel Heat Sink
Heat Transfer Results
0 100 200 300 400 500 600 7000
1
2
3
4
5
6
7
8
Bare Microchannel
CuNWs coated heat sink
Re
Nu
Results
July 19, 2010 Thesis Defense, USC
Results : Comparison between Bare and CuNWs Coated Microchannel Heat Sink
Heat Transfer Results
0 100 200 300 400 500 600 7000
1000
2000
3000
4000
5000
6000
7000
Bare Microchannel Heat sinkCuNWs coated heat Sink
Re
h
0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.080
1000
2000
3000
4000
5000
6000
7000
Bare Microchannel heat sinkCuNWs coated heat sink
x*
h
Results
July 19, 2010 Thesis Defense, USC
Results : Comparison between Bare and CuNWs Coated Microchannel Heat Sink
Heat Transfer Results
0 1 2 3 4 5 6 750
51
52
53
54
55
56
57
58
59
60
Re=106
Bare microchannel heat sink
CuNWs coated heat sink
Thermocouple number along heat sink
Tem
per
atu
re (
EC)
Results
July 19, 2010 Thesis Defense, USC
Results : Comparison between Bare and CuNWs Coated Microchannel Heat Sink
Pressure Drop Results
0 100 200 300 400 500 600 7000
500
1000
1500
2000
2500
3000
Bare MicrochannelCuNWs coated microchannel
Re
Pre
ssu
re d
rop
(P
a)
Results
Results : Assessment of Surface Morphology SEM Images After Heat Transfer Experiments
Summary and Future Works
Summary Cu Nanowires have been successfully grown on heat sink Experimental flow loop and test section has been designed and fabricated Heat transfer and pressure drop characteristics have been measured Enhancement in single phase microchannel heat transfer has been
demonstrated
Future Works
Experimental investigation of effect of CuNWs on two phase heat sink Fabrication of CuNWs on lower aspect ratio microchannels
July 19, 2010 Thesis Defense, USC
PublicationsJournal Publications
Ali, M. Y.; Yang, F.; Fang, R.; Li, C.; Khan, J. “Investigation on the Effect of Cu Nanowires on Heat transfer and Pressure drop Characteristics of Single Phase Microchannel Heat Sink” , To be Submitted
Conference Proceedings
Ali, M. Y.; Yang, F.; Fang, R.; Li, C.; Khan, J. “Effect of 1D Cu Nanostructures on Single Phase Convective Heat transfer of Rectangular Microchannel” ASME/JSME 8th Thermal Engineering Conference, Mar 13-17, 2011, Honululu, Hawaii, USA (Abstract has been accepted).
July 19, 2010 Thesis Defense, USC
Acknowledgement
Acknowledgement
Special thanks to Dr. Guiren Wang and Dr. Chen Li, Mechanical Engineering, USC and Dr. Qian Wang, Department of Chemistry & Biochemistry, USC.
Thanks to research group members, speciallyFanghao YangRuixian Fang
Thanks goes to ONR for financial support under ESRDC Consortium.
Acknowledge the facilities of EM Centre, USC.
July 19, 2010 Thesis Defense, USC
Conclusion
Thanks!
?
July 19, 2010 Thesis Defense, USC